A Case of Identity
by ThePet
Summary: Who killed the young Death-Eater in Snape's office? Can Severus and Sirius, with a little help from Hermione, put aside their differences long enough to find out? A Hogwarts Murder Mystery! *updated*
1. A Corpse in Snape's Office

A/N Keeping my habit of writing several things at once, and thus increasing my chances of losing my thread totally and looking an utter berk, this is the first chapter of a Hogwarts Murder Mystery fic ;-) representing grateful relief from Dark!Snape for a while, and the return of Witty!Snape.  
  
Why was this fic even conceived? It has a lot to do with Alan Rickman's utter suitability for the role of the Master, Sherlock Holmes, I must admit. ;-) Imagine if you will Minerva as Mrs. Hudson.heh-heh.  
  
  
  
"He's dead." Said Sirius Black, poking the lifeless body before him gingerly with the tip of his wand.  
  
"Thank you for that utterly ground-breaking observation, Black. I never would have noticed, from the *rictus sardonicus* on his face and the general lack of pulse or respiration, that this man no longer lives."  
  
"Don't mention it." Replied Sirius, cheerfully, as Snape leaned over the dead wizard's body for a closer look.  
  
"I know this man."  
  
"Of course you do. He's - he was - a Death-Eater. You've probably been to dinner parties with him, baby-sat his little Death-Eater children."  
  
"Shut up, Black."  
  
"I commiserate your loss."  
  
"Sod off." Said Snape calmly, then regretted his lack of wittiness. He was contemplating a more intelligent response when the door of the office - Snape's office, in which Snape, Sirius, and the stiffened corpse were to be found - opened, and a young face framed by bushy brown hair appeared.  
  
"Professor," began Hermione Granger, "Professor McGonagall wants to know if." predictably, having spotted the corpse, she broke off and clapped a hand to her mouth. "Oh! What happened?" This to Sirius, who was cheerfully poking the body again, as though expecting some response.  
  
"He's dead." Replied the animagus. "A dead Death-Eater, the best kind. You should probably fetch McGonagall."  
  
"Oh - yes.right." Wide-eyed, Hermione fled.  
  
"Wonderful." Muttered Snape. "Now we have little miss know-it-all involved. How are we supposed to keep her out of this? The silly girl doesn't know when to stop."  
  
"Hermione is a very clever, extremely competent young witch." Sirius told the other man sternly. "And sensible enough to keep quiet and let others deal with a situation beyond her capacity."  
  
Snape snorted. "Clever enough to let those more capable take care of the philosopher's stone? Clever enough to leave the Chamber of Secrets well alone? Clever enough to stay away from Potter and the constant trouble he brings? I tried to tell Lily Evans much the same thing."  
  
He got no further; the last remark was too much for Sirius.  
  
"Don't dare to mention Lily and James in front of me! And don't even think about criticising Harry. If it hadn't been for him and his friends, Voldemort would have been fully regenerated, the Chamber of Secrets would have been opened, and I'd be a soulless wonder by now!"  
  
"As for the first remark, I find it very unlikely that certain Hogwarts teachers would not have been able to secure the stone *without* a group of twelve year olds' posturing and melodrama. Secondly, if that idiot friend of Potter's hadn't resurrected Tom Riddle in the first place, the Chamber of Secrets would never have been opened. And thirdly - you say that as though it's a good thing."  
  
There was a short silence. Snape smirked. Sirius smirked back.  
  
"Well, while we're blaming everything on the Potters, how about this? If not for James, you'd have been dead before you were seventeen, and a hell of a lot of lives would have been saved with one less twisted Death-Eater around, hm?"  
  
"You talk too much." Said Snape, calmly, but with a nerve twitching in his cheek. He drew out his wand. "I think a Lockjaw hex would deal with that admirably."  
  
"You wouldn't dare."  
  
"No?" Snape raised the wand. Sirius bared his teeth. Fortunately for them both, however, McGonagall chose that moment to arrive, with the alarmed Hermione in tow.  
  
"Gentlemen!" Was her first, astonished exclamation. "What are you doing?"  
  
"Nothing." Muttered Snape, putting away his wand. Sirius relaxed, and turned what he hoped was a winning smile on McGonagall. She looked back stonily, then down at the corpse.  
  
"Goodness!"  
  
"He's dead." Sirius offered, helpfully.  
  
"I can see that, Mr. Black. What happened here?"  
  
This question fired directly at Snape, who made an incongruent attempt to look innocent.  
  
"Don't ask me. I didn't kill him."  
  
"Well, he's in your office! And a Death-Eater." She added, spotting the Dark Mark on the body's outflung arm. Snape simply shrugged.  
  
"Black found him. Perhaps he committed the deed."  
  
Sirius responded with a growl, Hermione with an indignant squeak.  
  
"Unlike some people around here, I don't go in for murder." Sirius snapped.  
  
"Oh, is that so?" Snape replied silkily. "Perhaps then we should all forget about your history of *attempted* killings - Pettigrew, myself, Lucius Malfoy, and who knows how many others?"  
  
"Lucius Malfoy?" Hermione piped up again, from behind McGonagall.  
  
"Long story." Said Sirius, casually. "Quite funny actually. I'll tell you about it sometime if you remind me."  
  
"It was not amusing in the least." Snape hissed.  
  
"Oh, for goodness' sake," McGonagall made a timely interruption. "will the pair of you stop arguing over your respective criminal histories and get back to the point. We are dealing with *this* corpse." She pointed to the dead body. "And I think," she added, "that it's about time someone fetched Dumbledore. I'll." she hesitated, obviously unwilling to leave Snape and Sirius alone with the body. "In fact, why don't." she began to Sirius, then realised that Snape, of course, was suspected of being involved. Then again, it was a fair point that Sirius had as much of a grudge as anyone against Death-Eaters, and although there were mitigating circumstances, he *had* tried to kill Peter Pettigrew.  
  
"Miss Granger," she said eventually, "find the headmaster and ask him to come immediately to Professor Snape's office. The password you require is 'toffee twirl'. After altering Professor Dumbledore, you will return to your colleagues in the Gryffindor common room. I assume that I can trust you to say nothing to *anyone* of this affair?"  
  
"Especially Potter and Weasley." Snape muttered under his breath, as Hermione nodded wordlessly.  
  
"Good." McGonagall dismissed Hermione efficiently, then knelt with dignity beside the corpse.  
  
"Have either of you moved, touched, or interacted with the body?" She asked.  
  
"I offered it a cigarette twenty three minutes ago." Said Sirius.  
  
"There's no need to be facetious, Mr. Black. I was merely enquiring."  
  
"I feel as though I'm being interrogated." Sirius told her, pathetically. "Even though I've been officially cleared, my name will always be mud, won't it?"  
  
Snape rolled his eyes at all this melodrama.  
  
"Black, this is a dead Death-Eater who has quite obviously been murdered. He was found in my office - my office, which is protected by various spells. My office, which no one but myself should be able to enter, once it has been locked up for the night. Which it was. Hence, I am a suspect."  
  
McGonagall made a noise of protest, but the potions master waved a hand to silence her.  
  
"You, Black, discovered the body. With no one else present. And you still haven't explained what you were doing in my office, in any case. This makes you a suspect."  
  
"Your point being?" Growled Sirius.  
  
"My point is that you know you are not the murderer, I know that I am not the murderer; but no one else does. It is only right that we should be treated as potential suspects. You don't see me complaining."  
  
"That," decided Sirius, "must be because you have a watertight alibi."  
  
Snape smirked, but said nothing.  
  
"Gentlemen, I do not believe that either of you killed this man. Before passing any sort of judgement, we will see what the headmaster has to say on the matter."  
  
They did not have to wait long. Professor Dumbledore arrived in minutes, looking as cheerful and relaxed as ever.  
  
"Oh, dear." He remarked, upon seeing the corpse.  
  
"Black found him." Snape said quickly.  
  
"He was like this when I got here." Sirius added, glaring at his arch- nemesis.  
  
"No one is making any accusations." Dumbledore soothed. "I would simply like to know what has transpired here."  
  
"Should I owl the Ministry, Albus?" McGonagall wondered. But Dumbledore shook his head.  
  
"We will make what we can of the situation before any official body is informed. Severus, Sirius, would you join Minerva and I in the potions classroom? This room should not be disturbed. I assume none of you touched the - er - body?"  
  
"Black poked him with his wand." Snape put in immediately.  
  
"Snape breathed over it." Sirius countered. "For all we know, that might have been what killed him."  
  
Dumbledore chose to ignore this. McGonagall rolled her eyes, and herded Snape and Sirius out of the room as though they were still pupils under her care.  
  
"No one has interfered with the corpse, Albus." She assured the headmaster, as she perched primly on a chair. Sirius climbed onto one of the tables and sat with his legs dangling; Snape leaned broodingly against the blackboard; and Dumbledore seated himself behind Snape's desk.  
  
"Perhaps you could begin, Sirius, by telling us what happened when you found the victim."  
  
"I'd hardly call him a victim." Sirius replied crisply. Dumbledore's blue gaze did not waver. Sirius shrugged and began to explain.  
  
"I got up at about ten - it is a Sunday after all." He added, as McGonagall raised an eyebrow. "Anyway," he continued, "I had breakfast, washed, dressed."  
  
"The headmaster did not ask for a comprehensive account of your slovenly morning routine, Black." Snape cut in. "He merely wishes to know."  
  
"Thank you, Severus, I will come to you in a moment. Go on please, Sirius."  
  
With a smirk at Snape, Sirius did so.  
  
"Anyway, at about ten thirty I headed down to Snape's office. I wanted to talk to him about something."  
  
"So you say. But what could you possibly desire to discuss with me, Black?"  
  
"It was about Harry." Sirius shot back. "And under the present circumstances I'd say it can wait, all right? As I was saying, before I was so rudely interrupted by the insinuations of that lanky greaseball, I reached Snape's office at about twenty-five to eleven, something like that. The potions classroom door was locked, so I opened it."  
  
"Cheek!"  
  
"I opened it and came through. I was surprised to find Snape's office door open - we all know how he loathes company. And that he doesn't get up until twelve on Sundays."  
  
Snape scowled - then smiled, unpleasantly.  
  
"If you knew I wouldn't be there, why were you coming to see me at that time? You're digging your own grave, Black."  
  
"That does seem inconsistent." Agreed McGonagall, reluctantly.  
  
"I'm sure there's a perfectly good explanation, Sirius." Dumbledore said calmly. Sirius coloured slightly.  
  
"Well - there is an explanation, but it isn't one you're going to approve of. I didn't come down to talk to Snape, I came to steal something from his office."  
  
"I knew it! And finding the Death-Eater there - for whatever purposes - you killed him. That solves one aspect of the mystery, at any rate. I'm sure you'll be able to convince the Ministry it was self-defence, Black. As for the attempted theft."  
  
"Snape, stop gloating and shut up a minute. All I wanted from your office was Ginny Weasley's potions homework. She made a mistake with the essay and didn't realise till afterwards; the poor girl's so terrified of you she couldn't sleep for worrying about how you'd humiliate her in class on Monday."  
  
McGonagall tutted and shook her head. Snape's smile faded.  
  
"That does not give you the right."  
  
"I know, I know. But I felt sorry for her." Sirius looked imploringly at Dumbledore. "She was worried sick. And I knew Snape is a lazy so-and-so at weekends, so I thought I could sneak into his office and grab the essay, Ginny could correct it - it'd only have taken a few minutes - then I could put it back before Snape marked it. If he wasn't such an ogre about homework."  
  
"Sirius, whatever your motivations, you do not have the right to break in to anyone's office. I disapprove strongly of such behaviour." Dumbledore spoke severely, but there was a twinkle in his eye. Snape noticed, and scowled even harder.  
  
"That explains the inconsistency. Please go on with your report."  
  
"But." Snape spluttered. "You mean you believe him? I've never heard such a foolish excuse."  
  
"Severus, please. Sirius."  
  
"Thank you, headmaster." Sirius flashed a gloating look in Snape's direction. "Seeing the office door open, my first thought was that Snape must've got up early, so I decided to leave before he spotted me. But something was wrong - the smell. I have a highly developed sense of smell, and the stink coming from the office, gross as it was, didn't match Snape."  
  
The potions master refrained from commenting on this slur on his personal hygiene. He remained silent, fingering his wand.  
  
"I couldn't just leave without investigating. I know the scent of - of death. And this was it. So I poked my head round the door, and there he was - the Death-Eater, dead as you like."  
  
"But you didn't raise the alarm then?" McGonagall asked.  
  
"I didn't have the chance. I was examining the body - I didn't touch it - when Snape walked in, demanding to know what I was doing there and generally being offensive. He had a look at the Death-Eater and had just told me that he knew him when Hermione came in."  
  
"I see. Thank you, Sirius. Severus?" Dumbledore turned to the potions master.  
  
"You knew the - ah, deceased?"  
  
"Not intimately. He had only recently been initiated into the Dark Lord's circle. He was." Snape swallowed, and said quietly, "he was seventeen years old. I believe his name was Trentham, Claudius Trentham, but beyond that."  
  
"Very well. Clearly our tasks now are twofold: examine the body itself, and find out as much information as possible about him from his name. Severus, you and Sirius will begin the former. Minerva, you and I will tackle the latter."  
  
"But, Albus," McGonagall was startled, "shouldn't we inform the Ministry? Surely they will want to conduct the investigation."  
  
"The Ministry," Dumbledore said quietly, "has refused to acknowledge the return of Voldemort. If the Ministry comes to know of what has happened here, it is likelty that the affair will be hushed up and ignored, and we will learn nothing. Thus, we will conduct an investigation ourselves into the murder of this Trentham. For the moment, I would prefer that no one else is to be involved. We do not yet know what this murder signifies, or why it came about - to release any information we do possess might be playing into Voldemort's hands."  
  
"You think this might be some sort of trap?"  
  
"Possibly, possibly. I would like to know what the Death-Eater was doing in your office, Severus. I would like to know who sent him there. I would like to know who killed him, and why. I would like to know how this event fits with the larger picture, and how it affects Voldemort's ongoing plans. We will determine the answers to these questions together, as quickly and as efficiently as possible." This last remark he directed at Sirius and Snape. The two exchanged dark glances.  
  
"I expect you to cooperate on this." Dumebldore reinforced, gazing intently at each of them.  
  
"You won't have any trouble from me." Said Sirius, eventually.  
  
"I will cooperate, of course." Snape agreed quickly. Dumbledore smiled.  
  
"Excellent! Good luck to you both, then. You may begin at once. Keep me informed of all developments. Minerva?"  
  
McGonagall got up, nodded crisply to Snape and Sirius, and followed Dumbledore out of the room, leaving the two men staring at one another.  
  
"Cooperate, he said." Remarked Sirius.  
  
"Efficiently." Agreed Snape.  
  
"Think we can do it?" The animagus asked, dryly. Snape shook his head, not in negation but in fretful weariness. He dropped into a chair.  
  
"You all right?" Sirius was curious rather than concerned, but determined not to fail Dumbledore by antagonising Snape, no matter how much he wanted to. No, Sirius was not going to strike first.  
  
The potions master passed a hand across his forehead before answering. "Our young friend in there was in my office for a purpose. I believe he was there to kill me."  
  
"What? Sent by who? I mean, you hardly knew him, it can't have been a personal thing."  
  
"Presumably he was sent by the Dark Lord."  
  
"But.I thought you had You-Know-Who convinced you were on his side."  
  
"Hardly." Snape sighed heavily, and Sirius noticed how drawn and pale he looked - even more of an ugly git than usual.  
  
"I sometimes feel that the Dark Lord and I are playing an absurd, vicious game." Snape went on, in an unnervingly dead voice. "I am working against him while pretending allegiance to him; he knows this, but in his turn, pretends ignorance. I suspect his mistrust, but again, feign ignorance."  
  
"So - you think Voldemort is just biding his time, waiting for the right moment to kill you? But why do it like this - why not just use the killing curse at one of your little gatherings? Seems a bit unnecessarily complicated to me, to send an assassin. Besides, surely there are more likely candidates for an assassin than that kid."  
  
"The Dark Lord often uses tasks to test the loyalty and ability of his followers. Possibly Trentham, as a new initiate, was expected to perform such a task - the task of murdering a renegade Death-Eater. I suspect that the Dark Lord waited this long because he wanted to see whether he could still make use of me. Finding that he couldn't he lost patience, and." Snape's voice tailed off. Sirius, looking at him, could read Snape's thoughts clearly: Voldemort's young assassin might have failed, but Voldemort still wanted Snape dead - hence, the next Death-Eater gathering Snape attended would likely be his last. But how could he not go, and still keep up his role as an agent for Dumbledore?  
  
"We'll get to the bottom of this." Sirius told Snape, firmly. "Maybe you're wrong. Maybe this is just some random occurrence that has nothing to do with Voldemort."  
  
But as he said it, Sirius knew how unlikely it sounded. Ever since resuming his role as double agent, Snape had known that a day would come when the Dark Lord would run out of patience, and snuff out his life as easily and with as much equanimity as one would a candle. Today had very nearly been that day, and though disaster had been averted this time by some unknown source, it could not be prevented for ever - or even for long. Snape might have another day, a week, a month to accept the fact of his own incipient demise, but that it would come was inevitable. And Sirius, though he disliked Snape, took no pleasure in that thought. He was searching for something comforting to say when Snape glanced up at him, shrugged, and offered a strange, lopsided smile. There are more important things to worry about than the life of one miserable ex-Death-Eater, that smile said. If it's coming, let it come. Let it come. 


	2. Snape Determines the Cause of Death

A/N It's taken a long time to get this next chapter up, but for what it's worth, here it is!!  
  
Thanks to everyone for reviewing the first chapter, and many thanks as always to my terrific beta, Amy.  
  
For any Holmes fans out there...except quite a lot of references to the Master before the end ;-) Anyone to get them all wins...er...The Golden Pistachio of Noticing-ness.  
*************  
"I refer you, Black, to the curious event of the cat in the morning."  
  
"What cat?"  
  
"Filch's cat, dunderhead!"  
  
"Filch's cat didn't do anything in the morning."  
  
"That," remarked Severus Snape, "was the curious incident."   
  
"You speak in riddles, git." Replied Sirius.  
  
"Always. You may or may not be aware that Mrs. Norris guards the potions lab on Saturday nights, with the cooperation of Mr. Filch. It is usually on Saturdays that certain malign creatures - Weasleys, for example - take it upon themselves to be nuisances. They interfere with ingredients, lesson plans, and anything else they can find. Since I have no intention of sitting up every Saturday night watching for the Damnable Duo, Filch kindly lends me his highly intelligent and immensely vicious pet."  
  
Sirius pondered.  
  
"What's that got to do with anything?" He wondered. Snape looked up with exasperation from the bench over which he was leaning; on it was the corpse of Claudius Trentham.  
  
"You found Trentham at ten thirty-five this morning. Mrs. Norris is always left in my office from midnight on Saturday until noon on Sunday. That is my arrangement with she and Argus. It never varies. You did not see Mrs. Norris this morning."  
  
"No, I didn't. I'd have remembered. That cat hates me."  
  
"As I said, a highly intelligent animal. Filch brought Mrs. Norris to my office at midnight as usual, last night; I went to bed at about one thirty a.m., leaving food and water for the cat. She sat on my desk, as always. Yet this morning there was no sign of her. Whatever the circumstances, Mrs. Norris does not neglect her duties. She is most diligent."  
  
Sirius raised an eyebrow. "Why not just elope with her? We all know you're a cat person." He leered.  
  
Snape gave a small sigh, but chose to ignore this last comment.  
  
"It's almost a quarter past twelve now. If Mrs. Norris had not returned to Filch, he'd have roused the whole castle."  
  
"Then you need to speak to Filch."  
  
"No, I need to examine this corpse. *You* need to speak to Filch."  
  
"But..."  
  
"Are you going to cooperate with me, Black?"  
  
Sirius scowled.  
  
"Cooperation, last time I checked, didn't mean you ordering me around. I'm not under your authority, Snape. And you know full well I'll get nothing out of that mouldy old caretaker and his moth-eaten moggy."  
  
"Show some respect!"  
  
"What is it with you and Filch, anyway? Are you his secret love-child, or something?"  
  
"Are you capable of conducting this post-mortem, Black?"  
  
"Probably not." Sirius admitted.  
  
"Then go and talk to Filch and let me get on with it."   
  
When Sirius finally departed, muttering darkly to himself, Snape returned his attention to the corpse - with, it must be said, a certain macabre interest. Trentham's body was strangely unmarked, but it was not the eerie result of the killing curse; Snape detected, in fact, no curses or hexes of any kind. The only really likely alternative, curses aside, was a potion of some sort. Dumbledore had made an efficient decision in asking Snape to perform the autopsy; with Snape's expertise covering both potions and the dark arts, there was little in the way of murder weapons which could escape his analysis.  
  
And yet - nothing. Trentham was simply dead, with no indication of how the deed had been committed. Snape sighed as he used his wand to extract a sample of the dead man's blood. There were many poisons undetectable to the naked eye - or nose - and to test for the presence of them all would take a very long time. There were even two potions Snape knew of which were completely undetectable: they disapparated from the body the moment the victim was dead, leaving a corpse that was unmarked both physically and chemically. But both those potions were near impossible to brew correctly, even if the right ingredients could be collected - which itself was more difficult and frustrating than holding a civil conversation with the Martyred Mongrel, Snape reflected sourly. He himself had the expertise to make one of the two potions, the more recently invented, known somewhat melodramatically as 'The Widowmaker'. But the ingredients it required...! Ground Pegasus feathers. Saliva of a Cerebrus - well, Hagrid could probably supply that. A drop of giant's blood. Perhaps the monster-minding oaf could provide that as well, Snape mused. Then there was the most rare element of all - a whole, live, Death-Watch beetle. Not the harmless creature Muggles were so superstitious about, but the real thing, a tiny animal found only in South America, and immensely difficult to catch, since any contact the thing had with the skin would prove fatal. The beetle's natural poison was among the most powerful in the world, but, used alone, it produced definite and definable symptoms in the victim, and the poison remained detectable after death. In combination with the other ingredients, if the potion was brewed at precisely the right time and in exactly the right manner, a single drop of 'The Widowmaker' caused instant death and left no trace of its presence.  
  
Snape had brewed the potion once, and only once, in circumstances he wished to forget. The process had very nearly killed him; as it was, he had been ill for months, despite the precautions he had taken to avoid directly touching the ingredients or inhaling any fumes. If 'The Widowmaker' was responsible for Trentham's death, then whoever killed him was - or was allied with - a potion-brewer of the greatest skill and courage.   
  
As for the other alternative...the more ancient undetectable poison, which even Snape could not make...he did not want to think about the possibilities of that. The Poison, as it was known - it did not even have a catchy name to make one feel a little more in control - was far from merely a liquid. It was a living thing, a thing which possessed a kind of rudimentary intelligence. And it could escape from the control of its creator. As far as Snape knew, there was no wizard or witch in the world capable of creating The Poison; in fact, the ability was thought to be lost, and no one person possessed a complete list of the ingredients.   
  
At least, so Snape hoped.  
  
Swiftly collecting samples of all the undetectable poisons he kept in his cupboards Snape lined them up methodically on the table and added a drop of Trentham's blood to each, three drops of an orange concoction which would determine whether the poison already existed in Trentham's bloodstream, and tapped the vials with his wand twice afterwards. The first tap to speed up the process. The second set up the vial to alert Snape automatically - with a rather unfortunate ear-piercing shriek - if a match was found. Hoping but not really believing that he would hear the shriek soon, Snape set about brewing the poisons he did not keep bottled in his office for a rainy day. The nastier ones. Poisons that could be slipped into food or drink, poisons that could be injected, poisons that worked by leaching through the skin. Poisons that transmitted themselves like viruses, poisons which became airborne and killed everything within a mile if the antidote was not provided. Snape made sure he brewed the antidotes first, and as he did so, he could not help reflecting that The Poison had no known antidote, and that once leaving its victim's body, it did not degrade, but travelled through the air, or through water, silent, scentless, invisible.   
  
Snape was not going to terrify everyone by voicing his concerns just yet. Forcing his hand to be steady and fixing his face in an expression of mild annoyance - the closest he could come to neutrality - he worked on, every nerve-ending on alert, hardly daring to hope that one of the vials would send out its siren.  
Being alone with his thoughts was never a good thing for Snape, and he was almost relieved when Black returned several hours later, blatantly having slipped off for some lunch.  
  
"Did you get anything of out Filch?" The potions master demanded, adding a drop of blood to the last-but-one vial.  
  
"Nothing except a lot of muttering and obscenities." Black replied cheerfully. "I told you so. Filch says Mrs. Norris would never neglect her duties, blah-de-blah, that she was in your office all the time, blah blah, he didn't see her till this morning."  
  
"I see." Snape added a drop of blood to the last vial. He had not really been expecting much information from Filch. If only Mrs. Norris could talk! Snape often suspected that she was the more intelligent of the two, which was no reflection, after all, on the caretaker.  
  
"Did you find out which one it was?" Black nodded at the worktable. Snape glared at him.  
  
"If I had, would I still be testing?" The potions master mimicked Sirius' casual tone. Sirius stared at him.  
  
"What is it?"  
  
"Hmm?"  
  
"What's going on, Snape? You're white as a sheet. You have found the poison, haven't you? What is it?"  
  
"Black, shut up. I've found nothing; nothing at all!" Unable to suppress his frustration, Snape swept an arm savagely across the table, knocking the first row of vials to the floor. They shattered, glass and liquids flying everywhere.  
  
"Don't worry." The potions master muttered, embarrassed as always at his outburst, "they were the most harmless ones. The vapour won't hurt you, just don't touch anything." With a wave of Snape's wand the mess was cleared up. The contents of the other vials would have to be more carefully disposed of.  
  
"What does it mean?" Black had dropped into a chair, looking worried, obviously picking up on Snape's mood. "That you haven't found anything? What does that mean? What killed this man, Snape? You said it wasn't a curse. Now you're saying it wasn't a potion either?"  
  
Snape realised he was going to have to take the moron through his reasoning step-by-step - and would probably have to do the same for the senior staff, as well...if it came to it, which was looking increasingly likely.  
  
"There is no trace of any curse on Trentham's body, and no trace of any poison."  
  
"But..."  
  
"Shut up, Black. There are over a hundred undetectable poisons, mostly variations on a dozen or so themes. 'Undetectable' simply refers to the fact that there is no obvious way to determine the presence of the potions; they have no smell or taste, they cause no noticeable symptoms. The victim simply dies."  
  
"That looks like what happened here."  
  
"Indeed. So I tested for every possible variation of undetectable poison - save two - using a complicated technique which I really cannot be bothered to explain to you. I have found nothing. Does that clear things up for you, Black? I - have - found - nothing!"  
  
Black stared blankly for a few moments. Snape could practically see the cogs turning slowly in the mongrel's brain.  
  
"So what killed him? One of the two you didn't test for?" Black asked, eventually.  
  
There could be no more delays, no more evasions. Snape swallowed hard.  
  
"I sincerely hope," he said quietly, "that Trentham was killed by a highly complex poison known colloquially as 'The Widowmaker', which is immensely difficult to brew, and even harder to collect the ingredients for. I know of no-one living but myself capable of producing this potion."  
  
"Modest, aren't you?" Black muttered.  
  
"It is the simple truth."  
  
"Hang on," Sirius frowned, "you said you hoped this potion had been used. Why?"  
  
This was it.  
  
"The only a alternative," Snape struggled to keep his voice steady, and failed, "is the remaining undetectable, completely undetectable, poison; one which was believed to have been lost. If there is someone in the world capable of brewing this poison..." he broke off, unable to continue. Black was staring at him with wide, alarmed eyes.  
  
"Go on, Snape, for God's sake." He muttered hoarsely. Snape took a breath and finished,  
  
"The Poison has no known antidote, and the way in which it can be destroyed is not known. After killing its first victim, it leaves the corpse and travels to another. According to legend, the creator of The Poison can usually control it, selecting victims at will - but The Poison grows in strength with each life it takes, and eventually develops a will of its own, killing according to its own needs. If it were let loose in Hogwarts..."  
  
"Everything in the Castle would die." Black whispered, grasping finally the severity of the situation. Snape nodded slowly. There was silence for a few moments, then, strangely, Black seemed to perk up.   
  
"If it was The Poison that killed Trentham - wouldn't it have taken another victim already?" The hope in his voice was painful to hear.  
  
"Not necessarily." Snape answered wearily. "If Voldemort sent Trentham here to carry The Poison, as I fear, he is in control of it for the moment. It may be - lying low, as it were. Voldemort fears Dumbledore's strength; if anyone can find a way to destroy The Poison, it is Albus."  
  
Another silence. Black chewed his lip.  
  
"Snape - how sure are you of this? Is there any way to tell whether the poison that killed Trentham was this Widowmaker thing or - or the other? I mean, you said the Widowmaker was immensely difficult to brew, but from what you've said, The Poison is completely impossible to create. Aren't we overreacting a bit here, panicking without all the facts?"  
  
Snape sighed wearily. Typical Gryffindor optimism; optimism that could get everyone killed, under the circumstances.  
  
"I agree that it is more likely that Trentham was killed using the Widowmaker poison. But we have no choice but to assume the alternative; you must see that, Black."  
  
Sirius got up and began pacing around the room, running his hands distractedly through his short black hair. "I do see it, Merlin help us all. You're right." He said it without a hint of hesitation. "We need to tell Dumbledore what you've discovered - or rather, what you haven't. Then...well, well see where we go from there, I suppose."  
  
All Black's arrogance and inappropriate humour had vanished; there was a look of horror in his eyes, and his voice shook slightly. Snape could not bring himself to feel any sense of satisfaction at this; he was too busy trying to mask his own utter terror. If Voldemort truly had been able to create The Poison, it could mean the end of Hogwarts - it could destroy everyone in the Castle within hours, if it chose. Worse. Every witch and wizard in the country - perhaps in the world - who refused to follow the Dark Lord could be wiped out using The Poison. No antidote. No defence. No hope.  
  
Snape shook himself. He refused to accept that there was no hope. It might yet be that his suspicions were erroneous - but his instincts as a master potions brewer, and sometime Death-Eater, were telling him that they were not.  
  
Never in his life had Severus Snape so desperately wanted to be wrong. 


End file.
